Usually, a 6mm gestational sac may be about 36 days pregnant, but the exact time still varies from person to person. The gestational sac is the fetal tissue that grows after the fertilized egg is deposited in the uterine lining during a woman’s normal pregnancy. The gestational sac will gradually increase in size with the development of the fetus, in the early stages of pregnancy can be based on the size of the gestational sac to initially calculate the number of days of pregnancy, the gestational sac 6mm is generally about 36 days pregnant. However, because the size of the gestational sac is affected by personal health, nutritional status, menstrual cycle and other factors, so the gestational sac 6mm is specifically how many days pregnant, but also from person to person, there may be some differences. Pregnant women are advised to undergo regular obstetric checkups after pregnancy to verify the gestational week in order to assess the subsequent fetal development.